Ultra-high-performance liquid chromatography for the determination of exenatide in monkey plasma by tandem quadrupole mass spectrometry

A highly sensitive ultra-high-performance liquid chromatographic-tandem mass spectrometry (UPLC/MS/MS) method was developed for the quantification of the synthetic peptide drug of exenatide in monkey plasma. Sample preparation was carried out by solid-phase extraction (SPE), and bivalirudin was used as the internal standard (IS). An excellent chromatographic separation was obtained on a reversed-phase C18 column with a gradient elution. Detection utilized a Qtrap 5500 system operated in the positive ion mode with multiple reaction monitoring (MRM). The proposed method was validated by assessing the specificity, linearity, intra- and inter-day precision and accuracy, recovery, and stability. The method resulted in a linear calibration range of 0.10-30 ng/mL, extracting with only 50 μL monkey plasma aliquots. The intra- and inter-day precisions (as relative standard deviation) were less than 7.5% and 9.6%, respectively. The method could be successfully utilized for the pharmacokinetic study of exenatide in monkeys following a single subcutaneous injection of Byetta.

Relationship and improvement strategies between drug nanocarrier characteristics and hemocompatibility:What can we learn from the literature

This article discusses the various blood interactions that may occur with various types of nano drug-loading systems. Nanoparticles enter the blood circulation as foreign objects. On the one hand, they may cause a series of inflammatory reactions and immune reactions, resulting in the rapid elimination of immune cells and the reticuloendothelial system, affecting their durability in the blood circulation. On the other hand, the premise of the drug-carrying system to play a therapeutic role depends on whether they cause coagulation and platelet activation, the absence of hemolysis and the elimination of immune cells. For different forms of nano drug-carrying systems, we can find the characteristics, elements and coping strategies of adverse blood reactions that we can find in previous researches. These adverse reactions may include destruction of blood cells, abnormal coagulation system, abnormal effects of plasma proteins, abnormal blood cell behavior, adverse immune and inflammatory reactions, and excessive vascular stimulation. In order to provide help for future research and formulation work on the blood compatibility of nano drug carriers.

Diversity and Bioactivity of Actinomycetes from Marine Sediments of the Yellow Sea

Among the 116 actinomycetes collected from marine sediments of the Yellow Sea,56 grew slowly and appeared after 2?3 weeks of incubation.Among the 56 strains,only 3 required seawater(SW) for growth,and 21 grew well in the medium prepared with SW rather than distilled water(DW),while the remaining 32 grew well either with SW or with DW.Six representatives with different morphological characteristics,including 1 SW-requiring strain and 5 well-growing with SW strains,were selected for phy-logenetic analysis based on 16S rRNA gene.Two strains belong to Micrococcaceae and Nocardiopsaceae respectively.The other 4 strains belong to the family of Streptomycetaceae.In the analyzed 6 strains,one was related to Nocardiopsis spp.and the other three were related to Streptomyces spp.,representing new taxa.Bioactivity testing of fermentation products from 3 SW-requiring strains and 21 well-growing with SW strains revealed that 17 strains possessed remarkable activities against gram-positive pathogen or/and tumor cells,suggesting that they were prolific resources for natural drug discovery.

Optimization,validation and application of an assay for the activity of HMG-CoA reductase in vitro by LC–MS/MS

A stable HMG-Co A reductase(HMGR) reaction in vitro was developed by a sensitive, selective and precise liquid chromatography–tandem mass spectrometry(LC–MS/MS) method. The optimized enzyme reaction condition contained 1.5 μg of HMGR, 20 n M of NADPH with 50 min of reaction time. The method was validated by several intra- and inter-day assays. The production transitions of m/z 147.0/59.1 and m/z154.0/59.1 were used to detect and quantify mevalonolactone(MVAL) and MVAL-D7, respectively. The accuracy and precision of the method were evaluated over the concentration range of 0.005–1.000 μg/m L for MVAL and 0.010–0.500 μg/m L for lovastatin acid in three validation batch runs. The lower limit of quantitation was found to be 0.005 μg/m L for MVAL and 0.010 μg/m L for lovastatin acid.Intra-day and inter-day precision ranged from 0.95% to 2.39% and 2.26% to 3.38% for MVAL, 1.46% to 3.89%and 0.57% to 5.10% for lovastatin acid, respectively. The results showed that the active ingredients in Xuezhikang capsules were 12.2 and 14.5 mg/g, respectively. This assay method could be successfully applied to the quality control study of Xuezhikang capsule for the first time.

Structures,properties,and applications of zwitterionic polymers

Zwitterionic polymers have attracted research attention in recent years owing to their unique molecular struc-tures.In the same repeat unit,positive and negative charges are simultaneously located on a pair of cationic and anionic groups;therefore,zwitterionic polymers have a large dipole moment and numerous charged groups.Al-though the molecular chain of the zwitterionic polymer can be maintained in an electrically neutral state overall,the coexistence of the oppositely charged groups confers extremely high polarity and excellent hydrophilicity to the polymer.At the same time,the electricality of the polymer can be further regulated by the environmental pH and salt ions,which greatly broadens the scope of applications in different fields.This review introduces various structures of zwitterionic polymers and analyzes the reasons why zwitterionic polymers exhibit pH responsive-ness,anti-polyelectrolyte effects,and superior electrical conductivity.The application fields are also summarized by generalizing the research status of zwitterionic polymers,including applications in antifouling coatings,drug delivery,wastewater treatment,and sensors,etc.